LAWRENCE — The leader of a New York-based civil rights organization sent the headmaster of The Lawrenceville School a letter last week criticizing the private institution’s decision to force its student body president to resign or else face disciplinary action in response to a photo she posted on social media.

The photo uploaded to Instagram in March showed Peterson wearing a Yale University sweatshirt and holding a hockey stick. The original the photo, which has been deleted, included the caption “Lawrenceville boi” and hashtags such as “#confederate” and “#romney2016,” among others. Peterson, who graduated last month, was the first black woman to hold the position in the school’s 204-year history.

The photo “supposedly depicted and mocked the appearance, if not lifestyle choices, of the supposedly ‘typical’ Lawrenceville white male student,” Meyers wrote in the July 2 letter, a copy of which was obtained by The Times.

“The mission and values of Lawrenceville, I thought, supported broad diversity and tolerance of different viewpoints. That kind of tolerance, and the commitment to answering — as opposed to shutting down and punishing — foolish or errant viewpoints, is what makes a school distinguished,” Meyers wrote. “No student who uses mockery or who tells ‘tasteless’ jokes, in an effort to make a political point, should be subjected by school officials to disciplinary proceedings or be bullied into resignation from a student office or be intimidated into silence.”

Peterson did not respond to requests for comment Tuesday.

Duffy responded to Meyers Monday morning in an e-mail, a copy of which was obtained by The Times, apologizing “that this complicated and unfortunate situation has been been (sic) portrayed in the media as it has been.”

“Please be assured that just as we respect the privacy of our students, we also respect their expressing their opinions and beliefs, as long as they don’t malign each other,” Duffy wrote. “Most importantly, as our mission suggests, we remain committed to preparing all our students to be responsible leaders in part by fostering an appreciation for diversity.”

Duffy went on to write that Meyers’ comments were shared among the Lawrenceville School faculty, who “will certainly keep them in mind as we continue to work to become not just a diverse, but a truly multicultural, community.”

After word of the incident last week sparked an online uproar among her supporters and critics alike, Peterson spoke with Melissa Harris-Perry of MSNBC on Sunday morning to discuss why she posted the photo to begin with.

“The photo was meant to be satire, and I think that satire is directed at people who are already on my side of the issue. I don’t think that I used this photo as a means to try to effect any change, per se,” Peterson said. “I think I did it as a way to put a satirical spin on something that I felt was an issue.”

Harris-Perry asked Peterson why what she did was any different than, for example, the case of the Arizona State University fraternity that was expelled in January after it threw a Martin Luther King Jr. party and “sort of performed this version of black culture,” Perry said.

“First of all, I’d like to say that I believe that the photo and what I did in my leadership position was not the smartest thing to do. But I think that it’s different because things like that and people making culturally insensitive jokes happen at Lawrenceville and there’s no repercussion,” Peterson said. “You have people dressing up as Indian chiefs and geishas, and taking pictures and it’s funny, but then when it’s happening the other way around to the majority of the population, all of a sudden it’s a problem and it’s brought to the forefront and there’s issues.”

Peterson said during the interview she plans to attend Wesleyan University, a private college in Connecticut.

When asked for further comment regarding Meyers’ letter, Lawrenceville spokeswoman Lisa Gillard declined and e-mailed The Times a statement officials released last week in response to media reports.

“We do not tolerate racial discrimination and have had few issues on campus for many years now,” the statement said. “We recognize that adolescents make mistakes and give our students every chance to be successful. But, they also know there are consequences for their actions and ultimately they will be held accountable for their behavior.”

The 2013-14 tuition for boarding students at The Lawrenceville School was $53,320, and $44,100 for day students, according to the school’s website. The first female students arrived on campus in 1987.

Peterson announced her resignation at the end of March in a schoolwide e-mail, according to a March 28 article in the school’s student newspaper, The Lawrence. Faculty and students felt “it was not fitting of a student leader to make comments mocking members of the community,” dean of students Nancy Thomas told The Lawrence.

Meyers took aim in the letter at Thomas’ comments, questioning the logic behind the school’s decision.

“Do you countenance the threatening of a student with ‘serious’ disciplinary action merely because you or the Dean of Students disagree with the student’s speech — disagree with her having posted photos of herself fully dressed — a photo that she posted as a joke, and which she captioned with derision or mockery as the typical ‘Lawrenceville boi?’” Meyers asked.

Though the original Instagram post was deleted from her account, Peterson reposted the photo two weeks ago using the hashtags “#peakedinhighschool” and “#tbt.” More than 230 users had “liked” the photo Tuesday night.

“If Lawrenceville truly embraces a ‘passion for learning,’ and ‘an appreciation for diversity,’ how do you as its Head Master square any school official’s bullying of a student over that student’s passionate expression of views about race and class, and ‘difference,’” Meyers asked Duffy in the letter. “And about what she regards as skin color privilege in a white-male dominated society?”